Mabel's Childhood Spell

I know only what they tell me / in shades of sea and stone. / I sit with hares, all unawares, / my kingdom for a bone. / The king of air who's never there / sits on his throne of earth. / The king of lack all dressed in black / is waiting for his birth.

Speculation
This focuses upon The King's cycle of life and death through the seasons, with the king waiting for his "birth" in the spring (seeing as this was written in the winter). That concept is explored in Bull in the Maze. "Shades of sea and stone" could refer to adder / hag stones, which are rocks with holes created by water in the center of them. In many places, they were believed to be able to help you see beyond the veil, most famously in modern media in Coraline. "I sit with hares, all unawares" is likely referencing Mabel spending time with Luna Thorne, the hare of the moon, while "my kingdom for a bone" implies an unfair trade.